As a rule, a supplementary European search must be performed for each international application entering the European phase and a search fee must be paid. For an exception see points 5.9.007 ff. Like any European search report, the supplementary European search report is accompanied by an opinion under Rule 62 EPC, the European search opinion (ESOP), on whether the application and the invention to which it relates meet the requirements of the EPC. As a further service, the information sheet "Information on Search Strategy" is annexed to all supplementary European search reports as from 1 January 2018 (see point 3.2.012). The supplementary European search report together with the search opinion is known as the "extended (supplementary) European search report" (EESR).

The supplementary European search is performed on the basis of the last set of (amended) claims available to the EPO on expiry of the time limit set in the Rule 161 EPC/Rule 162 EPC communication (see points 5.4.020 ff). That set of claims is considered the final set at the time the search is performed (see point 5.4.011). Any claim for which a claim fee due has not been paid will not be searched (see points 5.11.007 ff).

If third-party observations were filed during the international phase and forwarded by the IB to the EPO as designated or elected Office, they will be considered in the supplementary European search report, provided they are substantiated and meet all formal requirements. Furthermore, provided they were not filed anonymously and the third party has explicitly so requested, the EPO will expedite the issuing of the first office action in the (European) examination phase. 

If during the supplementary European search the EPO comes to the conclusion that the application contains more than one independent claim in the same category which does not fall under the exceptions listed under Rule 43(2) EPC, it may issue an invitation to indicate, within a time limit of two months, the basis on which the search is to be carried out (Rule 62a(1) EPC). Similarly, if it is impossible to carry out a meaningful search on the basis of all or some of the subject-matter claimed, the EPO will issue an invitation to file, within a time limit of two months, a statement indicating the subject-matter to be searched. Any declaration of no search, or a partial supplementary European search report issued subsequently due to failure to overcome the deficiency, takes the place of the European search report.